The present invention relates to component lead processing apparatus, and more particularly, to apparatus which can bend the leads to secure a component to a printed circuit board and detect the presence of the component on the printed circuit board.
Of interest are the following copending applications: Ser. No. 531,242, filed Sept. 12, 1983, entitled "Component Lead Processing Device," by Wojciech Starski; Ser. No. 363,960, filed Mar. 31, 1982, entitled "Multiple Component Lead Processing Apparatus," by George J. Whitley et al.; Ser. No. 302,294, filed Sept. 14, 1981, entitled "Component Lead Processing Device," by George J. Whitley et al.; Ser. No. 455,992, filed Jan. 6, 1983, entitled "Apparatus for Securing a Component to a Printed Circuit Board," by George J. Whitley; Ser. No. 469,722, filed Feb. 25, 1983, entitled "Bending Device," by Frederick W. Kopitzke, III et al.; Ser. No. 469,737, filed Feb. 25, 1983, entitled "Component Lead Bending Apparatus," by George J. Whitley et al.; and Ser. No.484,258, filed Apr. 12, 1983, entitled "Apparatus for Detecting the Presence of Components on a Printed Circuit Board," by George J. Whitley. All of the above applications are assigned to the assignee of the present invention.
As known, a printed circuit board includes numerous closely-spaced lead receiving apertures. Components may be automatically or manually assembled to the circuit board (which may be on a conveyor) by inserting component leads through the corresponding circuit board apertures. Later in the process it is required that the undersurface of the board pass over a wave soldering machine or the like which solders the protruding component leads to printed circuit board conductors. However, there is an interval between the time that component leads are inserted into the circuit board apertures and the time the circuit board passes through the soldering apparatus. During this time interval it is possible for the components to disengage from the circuit board.
Therefore, to prevent the components from becoming disengaged from the circuit board, it is desired that the protruding leads be crimped or bent over against the circuit board undersurface to preclude the leads from falling out of their corresponding apertures. Copending application Ser. No. 469,737, filed Feb. 25, 1983, mentioned above is an example of an apparatus for bending the protruding leads. Other apparatus have been employed to perform lead trimming and bending. Other examples of lead bending apparatus are disclosed in several of the above-mentioned copending applications and in U.S. Pat. Nos. 2,827,634; 3,167,779; 3,414,024; 3,574,934; 3,732,898; 4,051,593; 4,054,988; 4,153,082; 4,165,557; and 4,377,026, among others.
A problem sometimes encountered in the manufacturing process is that occasionally a component, whether inserted manually or by an automatic machine, may be inadvertently omitted. When a circuit board enters the wave soldering machine, apertures not having component leads therein become filled with solder and this makes it difficult to subsequently insert a component. It is also difficult to remove the solder from the filled apertures.
To resolve this latter problem, apparatus are employed to detect the presence of components on a printed circuit board after the lead bending operation, but prior to the soldering step. There are a number of known techniques which may be employed for detecting components on a printed circuit board. For example, U.S. Pat. No. 3,499,024 discloses a system for positioning microcircuit chips on a substrate which includes means for automatically sensing the presence of a chip. However, the system is designed to sense only a particular component of a given size and shape. It is not universally adaptable for sensing the presence of all of the different kinds of components which may be attached to the printed circuit board. For example, a disc shaped capacitor standing somewhat on edge and supported solely by relatively flexible leads would be difficult to detect. The apparatus described above could deflect the component due to the relatively flexible leads and the component presence not sensed. Further, such components come in a wide variety of sizes and may be at different heights above the printed circuit board and this adds to the difficulty of detecting them. Another example of apparatus for detecting components is shown in copending application Ser. No. 484,258 mentioned above. However, a component sensing apparatus to detect the presence of components requires a system for aligning such components to the detection apparatus. Such additional alignment apparatus adds cost and complexity to the lead processing system.